Subject: [Sigtran] Client/Server Operation in M3UA IPSP

From: Peter Woodhouse <[email-masked]>
Date: Fri, 23 Sep 2005 14:28:29 +0100

Hi All,

After the recent plugtest, it was suggested that this issue should be 
brought up here just for confirmation. So here goes.

In IPSP mode of M3UA, should there be any difference between how the 
client side and the server side operate?
For example, is it valid for the server side to send ASPUP?
Also, should the client send NTFY messages?

The way we interpret the RFC is that there is zero difference between 
client and server at M3UA level. The only difference is that the client 
side brings up the SCTP association.

Looking back through previous drafts of M3UA, section 1.4.8 of 
draft-ietf-sigtran-m3ua-06.txt did say "In the case of IPSP to IPSP 
communication, the peer endpoints using M3UA SHOULD be configured so 
that one always takes on the role of client and the other the role of 
server for initiating SCTP associations and M3UA messaging."
However the M3UA part was removed for draft 07 onwards.

In fact, I don't think Double Exchange would work if you dissallow the 
sending of ASPUP from the server side.

Comments?

Peter

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From: "Tolga Asveren" <[email-masked]>
Date: Fri, 23 Sep 2005 09:28:24 -0400

Peter,

My understanding is also similar to what you describe below. Actually,
considering the peer-to-peer nature of IPSP (which holds true only for
SE-mode), theoretically it may be not very correct to speak of
clients/servers.

The issue on SCTP level is another one. In fact, as far as I can recall, it
shouldn't be a problem even for SCTP, if both sides are willing to establish
the association. Regardless of that, this is separate from M3UA level.

    Thanks,
    Tolga

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On
> Behalf Of Peter Woodhouse
> Sent: Friday, September 23, 2005 9:28 AM
> To: [email-masked]
> Subject: [Sigtran] Client/Server Operation in M3UA IPSP
>
>
>
> Hi All,
>

---

From: "Tolga Asveren" <[email-masked]>
Date: Fri, 23 Sep 2005 13:37:58 -0400

one more comment below...

    Tolga

> sending of ASPUP from the server side.
[TOLGA] Yes, it won't. Actually, DE-mode is more like two coupled
client/server relationships rather than a real peer-to-peer model.

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Fri, 23 Sep 2005 14:27:56 -0600

Peter,

Peter Woodhouse wrote:                                                               (Fri, 23 Sep 2005 14:28:29)
> Also, should the client send NTFY messages?

In SE mode, one side sends ASPUP.  In DE mode, both sides.

> side brings up the SCTP association.

In both modes either side (or both sides) can initiate the SCTP
association.

> However the M3UA part was removed for draft 07 onwards.

This was struck because it was not necessary.  Either side (or both sides)
can initiate the SCTP association.

> sending of ASPUP from the server side.

In SE mode, one side sends ASPUP.  In DE mode, both sides.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/